π− decay rates of p-shell hypernuclei revisited

Explicit expressions for the parity-violating s-wave and the parity-conserving p-wave contributions to π− weak decay rates of Λ hypernuclei in the 1p shell are given in the weak-coupling limit, to update previous shell-model calculations and to compare with recent π− spectra and total decay rates measured by the FINUDA Collaboration for , , and . A useful sum rule for the summed strength of Λ1s→p1p hypernuclear π− weak decays is derived. Fair agreement between experiment and calculations is reached, using the primary s-wave amplitude and Cohen–Kurath nuclear wavefunctions. The role of the p-wave amplitude is studied in detail for and found to be secondary. Previous assignments of ground-state spin-parity values and are confirmed, and a new assignment is made, based on the substantial suppression calculated here for the weak decay rate.